One of the numerous steps in the process of designing an automobile involves packaging the engine within the space of the engine compartment that is made available by styling considerations. For example, a low silhouette hood line may be deemed an essential element of a particular model's styling and that imposes a constraint on the vertical extent of the engine compartment. This of course creates a need for a more vertically compact powerplant. At the same time that the powerplant is being dimensionally constrained, it is also required to meet certain performance standards (self- and/or government-imposed) relating to various matters such as fuel economy, tail pipe emissions, horsepower, noise, etc.
While the adoption of electronically controlled fuel managements systems, particularly multi-point injection systems, has enabled automobile manufacturers to comply with certain performance standards, demands from various corners, such as from automotive stylists and product planners, from lawmakers and government regulators, and from the marketplace itself, are almost continually imposing changes on applicable standards, usually in the direction of greater stringency. One of the problems which therefore confronts automotive engineers is how to simultaneously make an engine more compact, quieter, cleaner-burning, more fuel-efficient, and more powerful, without imposing intolerable cost penalties on the product.
An automobile powerplant configuration that is suited for these demands is a transverse-mounted, multi-point fuel-injected V-6 engine with front-wheel drive. The engine's length makes it suitable for transverse mounting, its six cylinders provide smoother running than a four-cylinder engine, and with proper design, including proper fuel and spark management, it can be made clean-burning, fuel-efficient, and powerful. The present invention relates to a new and unique intake manifold/fuel rail for such an engine, and this intake manifold/fuel rail makes significant contributions to engine performance and compactness.
The invention has a number of different, but inter-related, aspects. Certain ones are peculiar to a V-type engine, while certain others are more universally applicable. Described one way in general terms, the invention relates to a construction for an intake manifold containing an integral fuel rail. The disclosed embodiment is particularly adapted for a V-type engine, comprising a molded-phenolic lower manifold part that both contains an integral fuel rail and cooperates with a mating molded-thermoplastic upper manifold part to form the intake manifold/fuel rail.
One especially significant feature involves the manner of fabricating the lower manifold part to create individual through-passages for conveyance of combustion air to the individual engine cylinders. Briefly, each such through-passage is created by molding the phenolic around a respective pair of separably engaged core parts in the mold cavity, and then separating the two core parts of each pair by relatively moving them in generally opposite, but non-colinear, directions after the moldable phenolic has solidified. The two core parts of each pair are shaped to form respective portions of the corresponding through-passage, and to enable the through-passage to impose a substantially lower restriction on the flow through it, than was true in the case of an aluminum manifold that was previously used on the engine. Direct benefits of this aspect of the invention include opportunities for higher power output, cleaner burning of fuel, and better fuel efficiency.
Another significant feature of the invention relates to the configuration of the fuel passageway structure in the lower manifold part and to methodology for embodying that structure in the part.